1. Field of the invention
The present invention relates to an organometallic precursor for forming a micro- or a nano-sized conductive metal pattern using light and without using a photo-resist and a method of forming such a metal pattern using the same. More particularly, the present invention relates to an organometallic precursor, in which at least one of two ligands combined with a central transition metal is an imidazolylidene compound and the other is a homo or hetero imidazolylidene compound or xcex2-diketonate compound, and a method of forming the metal pattern using the same.
2. Description of the Prior Art
As well known to those skilled in the art, a conventional method of forming a metal pattern comprises the steps of depositing metal organics on a silicone or glass substrate according to a chemical vapor deposition process or an atomic layer deposition process to form a film on the substrate; coating a photo-resist on the resulting substrate according to a spin coating process; patterning the coated substrate according to a photolithography process; and etching the patterned substrate to remove the photo-resist. Another conventional method of forming a metal pattern comprises the steps of forming a metal film on a substrate according to a plasma deposition process, a sputtering process, or an electric plating process; coating a photosensitive resin on the resulting substrate; patterning the coated substrate using light; and etching the patterned substrate to form a desired metal pattern. These conventional methods require a high temperature and vacuum devices, and a patterning step using the photo-resist and an etching step for removing the photo-resist.
Meanwhile, various methods of forming a metal pattern without using a photoreaction have been suggested. For example, Japanese Patent Publication No. 62-263973 discloses a method of forming a metal pattern, in which an electronic beam is irradiated to an organometallic compound thin film without inducing any photoreaction. In addition, U.S. Pat. No. 5,064,685 (Kestnbaum et al.) discloses a method of forming a metal film using a thermal decomposition reaction, comprising the steps of coating metal organic ink on a substrate; and heating the resulting substrate with the use of a laser beam. According to this patent, the substrate is exposed to a high temperature, and materials other than metals are not allowed to be deposited on the substrate.
Another example of a method of forming a metal pattern is proposed by U.S. Pat. No. 5,534,312 (Hill, et al.), in which organic compounds sensitive to light are coordinate-bonded to a metal to synthesize an organometallic compound, the organometallic compound thus synthesized is coated on a substrate, and the resulting substrate is irradiated by the light to form a metal pattern without performing a coating step using a photo-resist. An organic ligand compound used in the above method is selected from the group consisting of acetylacetonates, dialkyldithiocarbamates, carboxylates, pyridines, amines, diamines, arsines, diarsines, phosphines, diphosphines, arenes, and alkoxy ligands. One or more ligands selected from the group consisting of oxalato, halogen, hydrogen, hydroxy, cyano, carbonyl, nitro, nitrate, nitrosyl, ethylene, acetylene, thiocyanato, isothiocyanato, aquo, azide, carbonato, amine, and thiocarbonyl are combined with a metal alone or in combination with two or more of the above organic ligand compounds to synthesize the organometallic compound. According to this patent, when the organometallic compound thus synthesized is coated on the substrate and exposed through a patterned mask, the light is directly reacted with the organometallic compound to decompose organic ligands coordinate-bonded to the metal to separate the organic ligands from the metal and to react the metal with surrounding metal atoms or oxygen in the atmosphere to form a metal oxide film pattern. Furthermore, the oxide film thus formed is subjected to a reduction reaction and a surface heat treatment under a mixed gas of hydrogen with nitrogen at 200xc2x0 C. or higher so as to improve the conductivity of the oxide film. However, the method disclosed in the above patent is disadvantageous in that the organometallic compound consists of ligands having a relatively high steric hindrance. This means that a space vacated by the ligand decomposed by the light is large, thereby undesirably increasing a shrinkage of a metal film thickness. So, the shrinkage of the metal film produced according to the above method reaches 90%, thus causing problems such as cracking and crazing of the metal film.
Therefore, it is an object of the present invention to avoid the above disadvantages, and to provide an organometallic compound in which the bulkiness of organic ligands, the primary cause of a metal film shrinkage, is reduced and the ligands are readily decomposed by light to separate from metals, and a method of forming a metal pattern using the organometallic compound.
According to an aspect of the present invention, provided is an organometallic precursor for forming a metal pattern, having a structure defined by the following Formula 1:
Lxe2x80x2xe2x80x94Mxe2x80x94Lxe2x80x83xe2x80x83Formula 1
wherein, M is a transition metal selected from the group consisting of Ag, Au, Cu, Pd, Ni, and Pt; L is an imidazolylidene compound having a structure defined by the following Formula 2; and Lxe2x80x2 is an imidazolylidene compound having a structure defined according to Formula 2 or a xcex2-diketonate compound having a structure defined by the following Formula 3: 
wherein, R1, R2, R3, and R4 are independently a hydrogen atom, or alkyl group, alkenyl group, alkynyl group, carboxyl group, alkoxy group, or ester group with 1 to 20 carbons, or aromatic hydrocarbon group with 6 to 20 carbons; and 
wherein, R5, R6, and R7 are independently a hydrogen atom, or alkyl group, alkenyl group, alkynyl group, carboxyl group, alkoxy group, or ester group with 1 to 20 carbons, or aromatic hydrocarbon group with 6 to 20 carbons.
According to another aspect of the present invention, a method of forming a metal pattern using such an organometallic precursor is provided.